Portable air filter



FIG. 1 is a front perspective view of a portable air filter;

FIG. 2 is a rear view of the portable air filter;

FIG. 3 is a side view of the portable air filter; and,

FIG. 4 is a bottom view of the portable air filter.

The broken lines in the figures show portions of a portable air filter that form no part of the claim. The end of the hose is shown with a symbolic break in its length. The appearance of any portion of the article beyond the break forms no part of the claim. The stippled shading shown in the drawings represents a contrast in appearance. 

CLAIM The ornamental design for a portable air filter, as shown and described. 